Random wire Receiver antenna good enough?
 

Hello,

I have just gotten my radio license and someone gave me an old
hammarlund receiver that hadn't been used in over 25 years. I used a
variac to bring up the power slowly, because I was told that the
capacitors needed to be reconditioned. Everything seemed to work fine
and I was able to pull in some transmissions with a random wire
antenna. I don't have a transmitter yet, so I am hoping to just use a
longer random wire antenna, laid along the attic until I can get money
together etc. My question is probably dumb, but I was wondering if
there is an "optimal length" for a random wire antenna for hf?

THanks for any help you can provide,

Joel Hainley
www.hamtesting.com

Random wire Receiver antenna good enough?
 

75 foot is the random number my son uses everytime. He does use an
external automatic antenna tuner for his radio, and has made some
incredible contacts.

Check out http://home.earthlink.net/~w0ipl/random-l.htm


On Sep 18, 6:05 pm, wrote:
Hello,

I have just gotten my radio license and someone gave me an old
hammarlund receiver that hadn't been used in over 25 years. I used a
variac to bring up the power slowly, because I was told that the
capacitors needed to be reconditioned. Everything seemed to work fine
and I was able to pull in some transmissions with a random wire
antenna. I don't have a transmitter yet, so I am hoping to just use a
longer random wire antenna, laid along the attic until I can get money
together etc. My question is probably dumb, but I was wondering if
there is an "optimal length" for a random wire antenna for hf?

THanks for any help you can provide,

Joel Hainleywww.hamtesting.com

Random wire Receiver antenna good enough?
 

For a receiving antenna, you can run a simple to test to see if you can
do better with respect to antenna length. Find a frequency where there
aren't any signals. Disconnect the antenna. If the noise level
decreases, then you're doing as well as you can. Any change in the
antenna length that increases the signal level will also increase the
noise level, which won't make you hear any better. It's possible that
the test will go one way at one frequency and the other way at another.
If that happens, you'll have to experiment to find the best compromise,
or arrange to have different lengths for different frequency ranges.
There's no way to predict what length is optimum, because if you're
using a single wire antenna, the actual conductor doing the receiving is
not only the wire but also any path from your receiver to the earth.
This typically includes some amount of house wiring.

This isn't to say that you can't make a better receiving antenna at all.
Putting a balanced antenna high and in the clear, with steps taken to
eliminate feedline pickup, will reduce any noise being picked up from
the house wiring and other nearby sources. And making a directional
antenna will increase signals more than noise -- although only in some
directions, at the expense of others. But in the meantime, while you're
staying with a random wire, the simple test will tell you what you want
to know.

Roy Lewallen, W7EL

wrote:
Hello,

I have just gotten my radio license and someone gave me an old
hammarlund receiver that hadn't been used in over 25 years. I used a
variac to bring up the power slowly, because I was told that the
capacitors needed to be reconditioned. Everything seemed to work fine
and I was able to pull in some transmissions with a random wire
antenna. I don't have a transmitter yet, so I am hoping to just use a
longer random wire antenna, laid along the attic until I can get money
together etc. My question is probably dumb, but I was wondering if
there is an "optimal length" for a random wire antenna for hf?

THanks for any help you can provide,

Joel Hainley
www.hamtesting.com

Random wire Receiver antenna good enough?
 

wrote in message
oups.com...
Hello,

I have just gotten my radio license and someone gave me an old
hammarlund receiver that hadn't been used in over 25 years. I used a
variac to bring up the power slowly, because I was told that the
capacitors needed to be reconditioned. Everything seemed to work fine
and I was able to pull in some transmissions with a random wire
antenna. I don't have a transmitter yet, so I am hoping to just use a
longer random wire antenna, laid along the attic until I can get money
together etc. My question is probably dumb, but I was wondering if
there is an "optimal length" for a random wire antenna for hf?

THanks for any help you can provide,

Joel Hainley
www.hamtesting.com

At one time, at least, the ARRL Handbook recommended something like 95 feet.
Way too long is better than way too short. For instance, my 75 meter dipole
receives OK on 20 meters. The 20 meter antenna is useless on 75.

Tam/WB2TT

Random wire Receiver antenna good enough?
 

On Wed, 19 Sep 2007 19:42:08 -0400, merlin-7 wrote:
"Tam/WB2TT" wrote:
wrote:

I have just gotten my radio license and someone gave me an old
hammarlund receiver that hadn't been used in over 25 years. I used a
variac to bring up the power slowly, because I was told that the
capacitors needed to be reconditioned. Everything seemed to work fine
and I was able to pull in some transmissions with a random wire
antenna. I don't have a transmitter yet, so I am hoping to just use a
longer random wire antenna, laid along the attic until I can get money
together etc. My question is probably dumb, but I was wondering if
there is an "optimal length" for a random wire antenna for hf?

At one time, at least, the ARRL Handbook recommended something like 95
feet. Way too long is better than way too short. For instance, my 75
meter dipole receives OK on 20 meters. The 20 meter antenna is
useless on 75.

It is always better to be to long than to short...

Yep. That's what _my_ spam claims, too. HI!HI!

Random wire Receiver antenna good enough?
 

On Sep 19, 11:12 am, "Tam/WB2TT" wrote:
wrote in message


At one time, at least, the ARRL Handbook recommended something like 95 feet.
Way too long is better than way too short. For instance, my 75 meter dipole
receives OK on 20 meters. The 20 meter antenna is useless on 75.

Tam/WB2TT

Thats mainly due to the way it's fed though.
As far as receiving, the short wire is plenty long enough,
just needs a better match.
If you feed a random wire straight to the center pin of most
radios, it will work pretty well. Even a short one.
Course, I probably would prefer a longer wire vs a short
one if I had my choice, but it's not really critical for a
good radio.
This is kind of similar to taking a 80 meter dipole
and shorting together the coax at the radio end,
and feeding as a vertical for 160m. The receiver will
be fairly quiet in the normal 80m config, but will jump to
life once you change the feed system around.
As far as the original poster, I would use whatever
fits. Not critical at all if you are truly feeding it
like a random wire.
Also, if you just stick the end of the wire in the center
pin of the radio, you shouldn't need any kind of
tuner in most all cases, if the radio is decent.
MK